HBC/975 TECHNICAL MANUAL MT052/E INSTALLATION START-UP AND MAINTENANCE INSTRUCTION

Transcription

1 GAS SAFETY CUT-OFF DEVICE HBC/975 TECHNICAL MANUAL MT052/E INSTALLATION START-UP AND MAINTENANCE INSTRUCTION

2 PRECAUTIONS GENERAL PRECAUTIONS - The apparatus described in this manual is a device subject to pressure installed in systems under pressure; - the apparatus in question is normally installed in systems for transporting flammable gases (natural gas, for example). PRECAUTIONS FOR THE OPERATORS Before proceeding with installation, commissioning or maintenance, operators must: - examine the safety provisions applicable to the installation in which they must work; - obtain the authorisations necessary for working when so required; - use the necessary means of individual protection (helmet, goggles, etc.); - ensure that the area in which they operate is fitted with the means of collective protection envisaged and with the necessary safety indications. HANDLING The handling of the apparatus and of its components must only be carried out after ensuring that the lifting gear is adequate for the loads to lift (lifting capacity and functionality). The apparatus must be handled using the lifting points provided on the apparatus itself. Motorised means must only be used by the persons in charge of them. INSTALLATION If the installation of the apparatus requires the application of compression fittings in the field, these must be installed following the instructions of the manufacturer of the fittings themselves. The choice of the fitting must be compatible with the use specified for the apparatus and with the specifications of the system when envisaged. COMMISSIONING Commissioning must be carried out by adequately trained personnel. During the commissioning activities, the personnel not strictly necessary must be ordered away and the no-go area must be properly signalled (signs, barriers, etc.). Check that the settings of the apparatus are those requested; if necessary, reset them to the required values in accordance with the procedures indicated in the manual. When commissioning, the risks associated with any discharges into the atmosphere of flammable or noxious gases must be assessed. In installations in natural gas distribution networks, the risk of the formation of explosive mixtures (gas/air) inside the piping must be considered.

3 PRECAUTIONS Packing for transportation of equipment is designed and shaped to avoid damage to any part during handling activities. After packing is open, check that no damage occurred to equipment. If damage occurred inform manufacturer and keep packing for any verification. CONFORMITY TO DIRECTIVE 97/23/EC (PED) Shut off valve HBC 975 with pressure switches for overpressure and underpressure may be employed as pressure accessory or safety accessory according to directive 97/23/EC. Conformity to Directive 97/23/FC and CE marking of valve and relevant accessory requires installation on system with minimum requirements according to: EN EN Pressure valve does not require any safety accessory installed upstream for protection against overpressure compared with design pressure PS, when reducing station installed upstream is sized for a max downstream incidental pressure MIPd < 1,1 PS. Valve, when installed on a reducing station must be installed at least according to installation. If equipment is employed as safety accessory, internal tightness shall be veri pressure value of 1,1XPS. Both verifications are essential to maintain CE marking. Periodical inspection and maintenance shall be carried out according to standard and laws in force (kind and period). Before commissioning of equipment after maintenance, external tightness shall be verified at a pressure value equal to valu e available on requirements of standard EN and EN All venting connection shall be connected as required by above mentioned standard.

4 1. DESCRIPTION Main features Fields of application and operation Operation Settings 7 2. INSTALLATION General 9 3. COMMISSIONING General Checking the setting Commissioning ACCESSORIES TROUBLE-SHOOTING MAINTENANCE General Disassembly COMPONENTS AND SPARE PARTS LIST 19 2

5 EDITION 2/2002 3

6 Fig. 1 4

7 1. DESCRIPTION The HBC 975 gas safety cut-off device is an apparatus which blocks the flow of gas if the controlled pressure reaches the set-point for its intervention, or if actuated manually. 1.1 Main features The valve is suitable for medium and high pressures. The main features of this valve are: - Gas cut-off in both directions - Balanced valve obturator - Indirect, self-fed, pneumatic actuation - Intervention for minimum and/or maximum pressure - Adjustable closing speed from 0.5 to 2 sec. - Local close button - Incorporated bypass - Manual reset only - Easy maintenance without removing body - Highly reliable internal parts - Possibility of build-in on Reflux and Aperflux regulators 1.2 Fields of application and operation - Non-corrosive filtered gas - Design pressure : 100 bar - Working temperature: from -10 to +60 C ( C on request) - SH control devices - Intervention for maximum pressure: 1 85 bar - Intervention for minimum pressure: bar 5

8 1.3 Operation The cut-off device consists principally of the following parts - on/off valve (12) - single action pneumatic actuator - line-off device When there is no pressure, the valve obturator is held in the closed position by the spring, pos. (13), and rests on the valve seat. The seal is guaranteed by the contact between the obturator and the valve seat. The control pressure is obtained by taking off gas at pressure Pe directly upstream from the valve. The gas passes through the valve (1) (which can deviate the pressure towards the downstream piping through a bypass line) and, appropriately filtered by the filter (2), enters the pressure regulator(4), the purpose of which is to stabilize the control pressure to the valve (4 bar); this can be checked on the pressure gauge(3). The stabilized gas enters the pneumatic valve 3/2 (8) and then passes to the actuator(11). When the actuator is filled, the valve opens. 6

9 1.3 Settings Setting springs table TT 984 7

10 table TT 985 8

11 2. INSTALLATION 2.1 General The HBC 975 cut-off device is always supplied complete with nipple for the sensing line. Before installing the valve you must ensure that: - the valve can be inserted in the space provided and that there is enough room for later maintenance operations - the piping upstream and downstream is at the same level and capable of supporting the weight of the valve; if it is not, fit appropriate supports - the inlet/outlet flanges on the piping are perfectly parallel - the interior of the mouths of the valve are clean and the valve has not suffered damage during transport - the upstream piping as far as the filter has been cleaned so as to expel residual impurities such as welding slag, sand, paint residues, water, etc. When the above controls have been carried out, the valve can be fitted in line, making sure that the body is oriented so that the flow is in the direction shown by the arrow impressed on the body itself. For proper regulation, it is indispensable for the downstream sensing line to be connected to a rectilinear stretch of the downstream piping itself with a length in accordance with the table and with a maximum gas speed at the take-off point not exceeding 30 m/sec. The valve closing pressure switch command is generated by comparing the pressure in the line, which can be read on the pressure gauge (10) and the setting springs (minimum and/or maximum) of the SH pressure switch device. When the ratio of the comparison deviates from the maximum value (or lower in the case of minimum setting) the pressure switch device moves the pneumatic control lever which discharges the gas from the obturator control chamber through the dumper (7). The spring (13) closes the valve(12). The valve can also be closed by mechanical movement by pressing the button (9B). The valve can only be reset manually by means of the reset pomel of the SH valve. To prevent the accumulation of impurities and condensate in the sensing line, it is recommended that: - the sensing line should always descend towards the nipple on the downstream piping with a slope of about 5 10% - the downstream piping nipple must always be welded to the top part of the piping itself. The most common types of installation for the HBC 975 cut-off device are shown in figures 2 and 3. 9

12 Figure 2 shows installation in a pressure regulation line; figure 3 shows installation on a generic trunk. 10

13 3. COMMISSIONING 3.1 General After installation, check that: - the inlet/outlet on/off valves and the bleed cock are closed - the cut-off device is closed. The open-closed situation can be seen from the position of the open-closed indicator on the head of the pressure switch control. The cut-off device is normally supplied already set at the required value but, for safety reasons, setting should be repeated in accordance with the procedure illustrated in the paragraphs which follow. ATTENTION: check that the conditions of use comply with the characteristics of the cutoff device before commissioning. These characteristics are shown by the symbols on the plates applied on every apparatus. Table 1 on page 12 lists the symbols used and their meanings. Consult table TT984-TT985 for the recommended set-point. - external tightness is guaranteed if no visible leakage when a foam medium is applied on the element under pressure - the internal tightness of an element which separates two chambers under different pressures is guaranteed when the pressure in the closed chamber with the lower pressure remains stable for a period of no less than 15 minutes taking account of the temperature variations. 11

14 table 1 Some symbols employed on these name plates are described here below Pemx = max inlet working pressure Who = intervention range of tripping unit in the event of overpressure. It may be obtained by using the set point springs shown in the applicable tables TT984-TT985 Wao = intervention range of ripping unit in the event of overpressure. It may be obtained by means of the set point spring installed by P.Fiorentini during the testing Whu = intervention range of tripping unit in the event of underpressure. It may be obtained by changing the set point springs as shown in the applicable tables TT984-TT985 Wau = intervention range of tripping unit in the event of underpressure. It may be obtained by means of the set point springs installed by P.Fiorentini during the testing. 12

15 3.2 Checking the setting Check as follows that the set-point of the cut-off device has the value desired: - separately connect the control head to a controlled auxiliary pressure - press the provided button to trip the cut-off device to the closed position - slowly open the on/off valve V1 upstream from the cut-off device with consequent pressurization of the line upstream from the cut-off device - position the three-way valve (1) in the bypass position and pressurize the line downstream from the cut-off device - ensure that the pressures above and below the valve are balanced - actuate the pressure switch reset knob (9B) - position the 3-way valve (1) in the working position - control the cut-off device opening through the provided indicator - stabilize the value of the auxiliary pressure at a lower value than the maximum pressure intervention point or between the maximum and minimum values when setting up for both types of intervention - reset the cut-off device device using the provided knob and: for safety devices which intervene for upper pressure: slowly increase the auxiliary pressure and check the trip pressure value; if necessary, increase the trip pressure value by turning the adjustment ring clockwise, or anticlockwise to reduce the intervention value. for safety devices for upper and lower: slowly increase the auxiliary pressure and record the trip pressure value. Restore the auxiliary pressure to the initial value, and carry out the cut-off device reset operation. Check intervention for pressure reduction by slowly reducing the auxiliary pressure. 13

16 3.3 Commissioning - Trip the cut-off device mechanically to the closed position by pressing the provided button. - Slowly open the on/off valve V1 upstream from the cut-off device with consequent pressurization of the line upstream from the valve. - Operating manually, position the 3-way valve in the bypass position and slowly pressurize the line downstream from the cut-off device and control the flanged and threaded seals in the section - Ensure that the pressures upstream and downstream the valve are in equilibrium - Actuate the reset knob (9B) of the pressure switch with consequent activation of the SH pneumatic device. - Turn the lever of the 3-way valve (1) slowly to the work position. - Control the opening of the cut-off device through the provided indicator 4. ACCESSORIES The following can be applied to the valve, on request: - valve and/or closed signalling microswitch - emergency system with remote control The system can also be built-in on Reflux and Aperflux regulators. 14

17 5. TROUBLE-SHOOTING PROBLEM POSSIBLE CAUSES REMEDY The cut-off device obturator Clogging of discharge nozzle of Clean does not close pneumatic valve 3/2. Leakage from the cut-off device obturator Rupture of the diaphragm (4) or O-ring (4) of the measuring head Obturator seal (7) deteriorated. Replace Replace O-rings (87) (88) deteriorated Replace Obturator seat (71) worn or scratched Grind or Replace Incorrect trip pressure Incorrect setting of max and/or min spring Reset by means of the adjustment ring Friction Leakage from GACO ring of the pneumatic control Not possible to reset The reason for increase or decrease of pressure downstream persists Broken linkage Clean Replace Checks the causes Replace the SH pressure switch No pressure after pneumatic resetting Replace filter cartridge 15

18 6. MAINTENANCE 6.1 General Before any maintenance operation, discharge the pressure as follows: a) close the upstream on/off valve V1 b) close the downstream on/off valve V2 c) check that the cut-off device is open d) very slowly discharge the pressure through the bleed cock to the atmosphere (6) In the event of intervention for minimum pressure, discharge the pressure upstream from the valve by turning the 3-way cock (1) to the bypass position. 6.2 Disassembly Before starting the disassembly operations, it is necessary to check that: - the valve has been cut off upstream and downstream and that the pressure between the two on-off valves has been discharged - you have a set of spanners as specified in the table - you have the recommended set of spare parts Depending on the type of problem which has occurred, maintenance may involve: a) the on/off valve b) the single action pneumatic actuator c) the line-off device a) On-off valve It is possible to remove the cut-off device valve without disconnecting the body from the piping. - disconnect all the feed and sensing line connections, by unscrewing all the conical seal connections - slacken the fixing screw of the LINE OFF system support bracket - slacken the fixing screw pos. (32) and remove the cut-off device device - slacken the nuts pos. (33) fixing the obturator pos. (71) to the rod pos.(6) - remove the obturator pos.(71) - relaxe completely the spring pos. (80) unscrewing the locknut pos.(9) - remove the spring pos.(80) - slacken the fixing screws pos. (86) and remove the obturator guide pos.(72) - slacken the fixing screws pos. (89) of the lock ring pos. (8) of the reinforced gasket 16

19 pos.(7) - remove the lock ring pos. (8) and the reinforced gasket pos.(7) - control and clean the metal parts - carefully control the state of the obturator valve seat - replace all the components in the spare parts kit Single action pneumatic actuator - unscrew the nut pos. (60) and remove the stroke reference ring pos. (59) - slacken the fixing nuts pos. (67) and remove the flange pos. (74)and the plating pos.(75) - remove the balancing piston pos.(15) - keeping the spacer pos. (69) firm, unscrew and remove the balancing rod guide pos. (11) remove the piston pos. (65) and the spacers pos. (69) and (19) - slacken the fixing screws pos.(27) - separate the flange pos. (73) from the cover pos. (70) - remove the rod guide pos. (20) from the cover pos. (70) - replace all the components in the spare parts kit b) Line-off device Filter - -slacken the cup pos. (1) and remove from cover pos. (2) - slacken the screw pos. (5)and remove the filter cartridge pos.(4) - replace all the components in the spare parts kit R91 pressure regulator - slacken the locknut pos.(17) - turn the adjusting screw pos. (15) anticlockwise to slacken to the end of its stroke - slacken the screws pos. (23) and remove the sleeve pos.(14), the spring support pos.(16), the spring pos. (21) and the diaphragm holder assembly - unscrew the locknut pos. (22) from the diaphragm support pos. (11) and remove the spring support pos. (13) and the diaphragm pos.(10) - unscrew the plug pos. (1) and remove the spring support pos.(6), the spring pos.(20), the lock ring pos.(7), the obturator pos. (8) and the reinforced gasket pos.(3) 17

20 - replace all the components in the spare parts kit VS/FI bleed valve - unscrew the plug pos.(3), discharge the spring pos. (4) and remove the obturator pos.(2) - carefully check the state of the valve seat - replace all the components in the spare parts kit Pressure switch device type SH1190 type disconnect the signal take-off - slacken the fixing screws pos. (43) - remove the cover pos. (2) - replace all the components in the spare parts kit NOTE: After cut-off device intervention, close the on/off valves upstream and downstream and discharge the pressure. The cut-off device must never be actuated before remedying the problem that caused it to trip. 18

21 7. COMPONENTS AND SPARE PARTS LIST 19

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37 I dati sono indicativi e non impegnativi. Ci riserviamo di apportare eventuali modifiche senza preavviso. The data are not binding. We reserve the right to make modifications without prior notice. Pietro Fiorentini S.p.A. UFFICI COMMERCIALI: OFFICES: I MILANO Italy - Via Rosellini, 1 - Phone (10 linee a.r.) - Telefax sales@fiorentini.com I ARCUGNANO (VI) Italy - Via E. Fermi, 8/10 - Phone (10 linee a.r.) - Telefax arcugnano@fiorentini.com I NAPOLI Centro direzionale - Isola G 1 Phone Telefax napoli@fiorentini.com ASSISTENZA POST-VENDITA E SERVIZIO RICAMBI: SPARE PARTS AND AFTER-SALES SERVICE: I ARCUGNANO (VI) - Italy - Via E. Fermi, 8/10 - Phone (10 linee a.r.) - Telefax service@fiorentini.com